1. Field of the Invention
The present invention relates to socket wrench sets and, in particular, to sockets adapted for use with any of a plurality of different-sized driven members. The invention has particular application to drive adapters for converting from one size of polygonal drive to another.
2. Description of the Prior Art
Socket wrench sets are typically provided with one or more square drive wrenches, each having a square drive lug adapted to be coupled to a variety of different-sized sockets. A typical wrench set may include a plurality of different wrenches with different-sized square drive lugs, each of which can mate with a plurality of different sockets. For the purpose of converting from one size of drive to another, drive adapters are provided. A drive adapter has a square drive socket at one end of a first size and a square drive lug at the other end of a second size, the socket being adapted for mating engagement with an associated male square drive element, as on a wrench tool, while the drive lug is adapted for mating engagement with an associated female element, such as an associated socket tool.
Such prior adapters are of one-piece construction and are characterized by a rather abrupt change in cross-section where the drive lug joins the remainder of the adapter body. The drive lug is subject to breakage from the socket at this transition when very high torque is applied. While it is possible to make the adapter of a material, or subject it to a heat treatment, to increase its strength so that it would resist breakage, this material or treatment would have to be applied to the entire adapter, even though it would not be necessary for the socket portion, thereby significantly increasing the cost of the adapter.
It is known to provide socket wrench sets wherein at least one of the sockets is a bit socket, i.e., a socket which is adapted to receive any of a number of different-sized bits. Such bits may be of any of a number of different types, such as screwdriver bits, wrench bits and other types of drive configurations. Typically, each such bit has a polygonal shank provided at an application end with a drive configuration adapted for a particular drive application. The shank is dimensioned to fit into the workpiece-engaging end of a wrenching socket, being retained in place therein by a set screw or roll pin or the like, received through radial bores in the socket, or by a friction ring, such as a wire ring or O-ring. For example, the socket may have a hexagonal workpiece engaging end, in which case each of the bits will have a hexagonal shaft mateably engageable in the socket. The socket also has a drive recess at a drive end thereof, which may be a square recess adapted to receive a drive lug of an associated driving tool, such as a ratchet wrench or the like. In this way, a single socket may be used with a driving tool to drive a plurality of different bits.
However, in this prior arrangement, in the event a set screw or roll pin is used for bit retention, engagement and disengagement of the bits in the socket is relatively cumbersome and time consuming, requiring the mounting and demounting of the set screw or roll pin, each time the bit is changed. Indeed, it is so cumbersome that normally a user will purchase a separate socket for each bit to obviate bit changing. Furthermore, the set screw or roll pin constitutes an additional part which must be manufactured, inventoried, and kept track of, which adds to the cost of manufacture and assembly, and further entails the risk of loss by the user. The use of a friction ring for bit retention simplifies bit changing but does not provide a very secure retention.
It is also known to provide a bit set for use with a box ratchet wrench, each of the bits having a shank which is insertable into the box ratchet, and the depth of insertion being limited by a lateral projection on the bit shank approximately midway along its length. Such ratchet and bit sets are sold, for example, by Snap-on Tools Corporation under the designation CRA180PB. Typically, the box ratchet is provided with an O-ring or the like to frictionally hold the bit in place in the ratchet.